Re: [PATCH 4/5] gdb: add "info index-cache stats", deprecate "show index-cache stats"

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2021-11-04 14:33, Tom Tromey wrote:
>>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:
> 
> Simon> The "show index-cache stats" command is used to show some statistics
> Simon> about the index-cache usage.  I believe this is not a good use of a show
> Simon> command, as it is not a setting.
> 
> I think "show" is generally used for any information about the debugger,
> not just settings.
> 
> A long, long time ago there was some effort to split 'info' and 'show'
> this way.  The details of this discussion are long lost, as far as I
> know, but the outcome lives on in the help and manual:
> 
> 'info'
>      This command (abbreviated 'i') is for describing the state of your
>      program.
> 
> 'show'
>      In contrast to 'info', 'show' is for describing the state of GDB
>      itself.  You can change most of the things you can 'show', by using [...]
> 
> So I tend to think "show index-cache stats" is more correct.

Ah, I didn't know about that, thanks.

Then I still wonder what to do about:

    (gdb) interpreter-exec mi "-gdb-show index-cache"
    ~"\n"
    ~"    Cache hits (this session): 0\n"
    ~"  Cache misses (this session): 0\n"
    ~"\n"
    ~"The index cache is currently disabled.\n"
    ^done

The answer is probably to output those numbers using uiout fields in the
command implementation.  If I hack that, I get:

    ...
    ^done,hits="0",misses="0"

which looks good.

What's nice about "show" is that we don't need to add a new MI command
for everything: -gdb-show just works with any child of the "show"
command.  It would be nice to have the same thing with info, have an
"-info" MI command that works with "info" command children.  Of course,
these commands would have to be MI-aware (emit information using uiout
fields), but that's much easier than adding new MI commands for each.

So, I'll drop this patch then, and consider changing the "show
index-cache stats" implementation to use uiout fields (although I am not
aware of any frontend interested in using the the index-cache stats
data).

Simon